Gas turbine installation

ABSTRACT

Disclosed is a gas turbine power generating system capable of achieving a high output power and a high power generating efficiency under conditions with a small amount of supplied water and little change in design of a gas turbine. A fine water droplet spraying apparatus ( 11 ) is disposed in a suction air chamber ( 22 ) on the upstream side of an air compressor ( 2 ), and a moisture adding apparatus ( 7 ) for adding moisture to high pressure air supplied from the compressor ( 2 ) is included. A regenerator ( 5 ) for heating the air to which moisture has been added by using gas turbine exhaust gas as a heat source is also provided. With this configuration, there can be obtained an effect of reducing power for the compressor ( 2 ) and an effect of increasing the output power due to addition of moisture to air ( 20 ) for combustion. Further, since the amount of fuel used is reduced by adopting a regenerating cycle, the power generating efficiency is improved.

This is a divisional application of U.S. Ser. No. 09/403,417, filed Jan.5, 2000 (U.S. Pat. No. 6,389,799).

TECHNICAL FIELD

The present invention relates to a gas turbine, and particularly to ahigh moisture gas turbine cycle using high moisture air for combustion.

BACKGROUND ART

High moisture gas turbine cycles have been disclosed, for example, inJapanese Patent Laid-open Nos. Sho 57-79224, Sho 57-79225, and Sho58-101228, and U.S. Pat. No. 4,448,018, in which thermal energy of gasturbine combustion exhaust gas or the like is recovered to produce watervapor; the water vapor is mixed in combustion air for the gas turbine;and a turbine is driven by high moisture combustion exhaust gas obtainedby a combustor, whereby the output power and the power generatingefficiency are enhanced.

A configuration of one of the above high moisture gas turbine cycles hasbeen disclosed, in which a low pressure compressor and a high pressurecompressor are arranged in series, and a direct or indirect heatexchanger is interposed between both the compressors, wherein heatrecover is performed by injecting water to compressed air emerged fromthe high pressure compressor.

DISCLOSURE OF INVENTION

In each known example, however, it is required to inject a large amountof water to compressed air to be supplied to a combustor for obtaining adesired output power or a desired power generating efficiency.

When air containing large amount of water is supplied to the combustor,the combustion stability of the combustor becomes low. In particular,for a power generating gas turbine, premixed combustion of air and fuelin a narrow stable combustion range, which is performed for reducing theamount of Nox of exhaust gas, is largely affected by the supply of airincluding a large amount of water.

Accordingly, the present invention provides a high moisture gas turbineinstallation capable of enhancing combustion stability while ensuringdesired output power and power generating efficiency.

The present invention also provides a high moisture gas turbineinstallation capable of enhancing combustion stability while ensuringdesired output power and power generating efficiency by reducing theamount of water required to obtain the desired output power and powergenerating efficiency.

The present invention also provides a high moisture gas turbine capableof miniaturizing a humidifier, an apparatus for recovering water fromgas turbine exhaust gas, and the like by reducing the amount of suppliedwater, and further increasing the output power and power generatingefficiency by reducing loss in compressed air and exhaust gas.

In a high moisture gas turbine cycle, a large amount of moisture isadded to air for combustion. In this case, if moisture is partiallyadded to air supplied from atmospheric air, a humidifier can beminiaturized and a heat exchanger for supplying hot water to thehumidifier can be also miniaturized as compared with the method in whichmoisture is added to compressed air.

As a result, a pressure loss in equipment connected between a gasturbine and air compressors such as the humidifier and heat exchanger isreduced, and thereby the power generating efficiency of the gas turbinecan be improved. Also, the power of the air compressor can be reducedeven if the air compressor is not divided or a plurality of the aircompressors are not arranged in series, and thereby the output power andthe power generating efficiency of the gas turbine can be improved.

To be more specific, the present invention provides a gas turbineinstallation including a compressor for compressing air supplied theretoand discharging the compressed air, a combustor for burning fueltogether with the air discharged from the compressor, and a turbinedriven by combustion gas generated by the combustor, the gas turbineinstallation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor therebymaking the temperature of the air to be supplied to the compressor lowerthan the temperature of atmospheric air, the sprayed water dropletsbeing introduced in the compressor together with the air whosetemperature has been lowered and being evaporated in a period in whichthe water droplets flow down in the compressor together with the air;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source; and

a path through which the compressed air heated by the regenerator issupplied to the combustor.

For a gas turbine system in which the spraying apparatus 11 is simplyprovided to the compressor, since the compression work is reduced, theeffect of increasing the output power becomes large; however, since thetemperature of the air at the outlet of the compressor is lowered, thatis, the temperature of the air to e supplied to the compressor islowered, the used amount of fuel at the combustor becomes large, so thatit is not expect to increase the power generating efficiency.

The present invention also provides a gas turbine installation includinga compressor for compressing air supplied thereto and discharging thecompressed air, a combustor for burning fuel together with the airdischarged from the compressor, and a turbine driven by combustion gasgenerated by the combustor, the gas turbine installation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source; and

a path through which the compressed air heated by the regenerator issupplied to the combustor.

The present invention also provides a gas turbine installation includinga compressor for compressing air supplied thereto and discharging thecompressed air, a combustor for burning fuel together with the airdischarged from the compressor, and a turbine driven by combustion gasgenerated by the combustor, the gas turbine installation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source;

a path through which the compressed air heated by the regenerator issupplied to the combustor; and

a path used for recovering moisture from combustion exhaust gas havingpassed through the regenerator and supplying the recovered moisture toat least one of the spraying apparatus and the water adding apparatus.

With these configurations, the amount of supplied water can be reduced.Also since the recovered water containing heat of exhaust gas can bereused and the heat generated by itself can be returned to the upstreamside from the combustor, the power generating efficiency of the gasturbine can be further improved. Further, the recovered water is heatedby using compressed air or gas turbine exhaust gas as a heat source, aheating apparatus for heating water before addition of the water to thecompressed air can be miniaturized. This makes it possible to reduce thepressure loss and hence to further enhance the power generatingefficiency.

In the above-described gas turbine installation, preferably, thespraying apparatus comprises sprayers which are arranged in a pluralityof steps along the flow of the air in the suction air chamber in such amanner that the temperature of water sprayed from one, positioned on thedownstream side, of the sprayers is higher than the temperature of watersprayed from one, positioned on the upstream side, of the sprayers.

With this configuration, since the flow rate in weight at the inlet ofthe compressor is increased and thereby the water droplets being easy tobe evaporated in the compressor can be supplied from the inlet of thecompressor, it is possible to stably increase the evaporation amount inthe compressor.

To be more specific, suction air is cooled by the water sprayers at thefront steps to increase the flow rate in weight of the air, and hightemperature water is sprayed to the air from the water sprayers at therear steps disposed near the inlet of the compressor, whereby waterbeing easy to be evaporated in the compressor can be largely containedin the air to be supplied to the compressor.

In this regard, by making large the ratio of the amount of watersupplied to the air by the spraying apparatus to the amount of wateradded to the compressed air by the water adding apparatus, it ispossible to further enhance the output power and the power generatingefficiency.

The above-described gas turbine installation preferably furtherincludes:

a control unit for controlling the amount of water added to air in sucha manner that the amount of water sprayed to the air by the sprayingapparatus is in a range of 1/50 to 1/5 of the amount of water added tothe compressed air by the water adding apparatus.

The above amount of water sprayed to the air by the spraying apparatusis preferably in a range of 1/25 to 1/10 of the amount of water added tothe compressed air by the water adding apparatus.

The above-described gas turbine installation preferably furtherincludes:

a control unit for controlling the amount of water added to air in sucha manner that the amount of water sprayed to the air by the sprayingapparatus is in a range of 1/50 to 1/5 of the amount of water added tothe compressed air by the water adding apparatus;

wherein the ratio of the amount of circulated water to and from thewater adding apparatus to the amount of water added to the compressedair by the water adding apparatus is controlled to be in a range of 70%to 95%.

Further, the above ratio is preferably in a range of 1/25 to 1/10.

In the above-described gas turbine installation, preferably, the ratioof the amount of water sprayed to the air by the spraying apparatus tothe flow rate in weight of the air is controlled to be in a range of0.2% to 5.0%, and the ratio of the amount of water added to thecompressed air by the water adding apparatus to the flow rate in weightof the compressed air discharged from the compressor is controlled to bein a range of 30% or less.

The above ratio of the amount of water sprayed to the air by thespraying apparatus to the flow rate in weight of the air is morepreferably in a range of 0.4% to 2.5%

The present invention also provides a gas turbine installation includinga compressor for compressing air supplied thereto and discharging thecompressed air, a combustor for burning fuel together with the airdischarged from the compressor, and a turbine driven by combustion gasgenerated by the combustor, the gas turbine installation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source;

a path through which the compressed air heated by the regenerator issupplied to the combustor; and

a control unit for controlling the temperature of water in such a mannerthat the temperature of water supplied to the water adding apparatus ishigher than the temperature of water supplied to the spraying apparatus.

The control unit can be configured as a water supplying apparatuscapable of supplying water at a plurality of temperature levels or anapparatus for recovering water from exhaust gas.

The present invention also provides a gas turbine installation includinga compressor for compressing air supplied thereto and discharging thecompressed air, a combustor for burning fuel together with the airdischarged from the compressor, and a turbine driven by combustion gasgenerated by the combustor, the gas turbine installation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source;

a path through which the compressed air heated by the regenerator issupplied to the combustor;

a water supply path used for recovering moisture from combustion exhaustgas having passed through the regenerator and supplying the recoveredmoisture to the spraying apparatus and the water adding apparatus; and

a cooling apparatus for cooling the compressed air flowing on theupstream side of the water adding apparatus by heat exchange with thewater supplied to the water adding apparatus.

The above-described gas turbine installation, preferably, furtherincludes, in place of the water supply path, added water supply pathused for recovering moisture from combustion exhaust gas having passedthrough the regenerator and supplying the recovered moisture to thewater adding apparatus; and a spray water supply path through whichspray water is led from an external source outside the system in thespraying apparatus.

The present invention also provides a gas turbine installation includinga compressor for compressing air supplied thereto and discharging thecompressed air, a combustor for burning fuel together with the airdischarged from the compressor, and a turbine driven by combustion gasgenerated by the combustor, the gas turbine installation comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source;

the combustor to which the compressed air heated by the regenerator issupplied;

a water supply path used for recovering moisture from combustion exhaustgas having passed through the regenerator and supplying the recoveredmoisture to the spraying apparatus and the water adding apparatus; and

a supplied water heater for heating water to be supplied to the wateradding apparatus by using combustion exhaust gas having passed throughthe regenerator as a heat source.

The above-described gas turbine preferably further includes:

a control unit for reducing, upon decrease in load, the amount of waterto be added to the compressed air by the water adding apparatus and thenreducing the amount of water to be sprayed to the air by the sprayingapparatus; or a control unit for increasing, upon increase in load, theamount of water to be sprayed to the air by the spraying apparatus andthen increasing the amount of water to be added to the compressed air bythe water adding apparatus.

The present invention also provides an efficiency increasing apparatus,provided in a gas turbine installation, for recovering thermal energy ofgas turbine exhaust gas thereby improving power generating efficiency,the gas turbine installation including a compressor for compressing airsupplied thereto and discharging the compressed air, a combustor forburning fuel together with the air discharged from the compressor, and aturbine driven by combustion gas generated by the combustor;

the efficiency increasing apparatus comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus; and

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source.

The present invention also provides an efficiency increasing apparatus,provided in a gas turbine installation, for recovering thermal energy ofgas turbine exhaust gas thereby improving power generating efficiency,the gas turbine installation including a compressor for compressing airsupplied thereto and discharging the compressed air, a combustor forburning fuel together with the air discharged from the compressor, and aturbine driven by combustion gas generated by the combustor;

the efficiency increasing apparatus comprising:

a spraying apparatus, which is provided in an air suction chamberdisposed on the upstream side of the compressor, and which is used forspraying water droplets to air to be supplied to the compressor,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor, and evaporating the non-evaporated waterdroplets led in the compressor together with the air in a period inwhich the water droplets flow down in the compressor together with theair;

a water adding apparatus for adding water to the compressed airdischarged from the compressor, the compressed air containing moistureadded in the form of water droplets by the spraying apparatus;

a regenerator for receiving the compressed air containing moisture addedby the water adding apparatus and heating the compressed air by using agas turbine exhaust gas as a heat source; and

a path used for recovering moisture from combustion exhaust gas havingpassed through the regenerator and supplying the recovered moisture toat least the water adding apparatus of a group of the spraying apparatusand the water adding apparatus.

The above-described efficiency increasing apparatus preferably furtherincludes:

a control unit for controlling the amount of water added to air in sucha manner that the amount of water sprayed to the air by the sprayingapparatus is in a range of 1/50 to 1/5 of the amount of water sprayed tothe compressed air by the water adding apparatus. The amount of watersprayed to the air by the spraying apparatus is more preferably in arange of 1/25 to 1/10 of the amount of water sprayed to the compressedair by the water adding apparatus.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram showing one embodiment of the presentinvention;

FIG. 2 is a schematic diagram showing effects of a spraying apparatus 11for spraying water to suction air and a humidifier 7;

FIG. 3 is a schematic diagram showing one embodiment of the presentinvention;

FIG. 4 is a schematic view showing one embodiment of the presentinvention;

FIG. 5 is a schematic view showing one embodiment of the presentinvention; and

FIG. 6 is a schematic view showing one embodiment of a water recoveryapparatus 8 portion.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described withreference to the drawings. FIG. 1 is a schematic flow diagram of a gasturbine cycle showing a first embodiment. A gas turbine power generatinginstallation includes, as shown in FIG. 1, a compressor 2 forcompressing air and discharging the compressed air; a combustor 4 towhich air compressed by the compressor is supplied; a gas turbine 1driven by a combustion exhaust gas discharged from the combustor; and apower generator 3 connected to the gas turbine 1 via a shaft. The powergenerator 3 is connected to a power transmission line not shown in FIG.1. It should be noted that in this figure, a pump and the like are notshown.

An air suction chamber 22 for sucking air and supplying the air to thecompressor 2 is connected to the compressor 2. At the leading end of theair suction chamber, typically, a suction air filtering chamber 21containing a filter 23 is disposed. A louver 24 is disposed on anupstream side portion of the suction air filtering chamber 21.

A spray apparatus 11 for spraying water to suction air, which isdisposed in the suction air chamber, includes a spray typicallyconfigured as a spray nozzle described in Japanese Patent Laid-open No.Hei 9-236024. The Zautor's mean particle diameter (S.M.D) of waterdroplets sprayed by the spray nozzle is about 10 μm. In this embodiment,the spraying apparatus 11 is disposed at the inlet of the compressor,for example, in the suction air chamber 22 separated apart from a firststage stationary blade. To be more specific, in the example shown inFIG. 1, the spraying apparatus 1 is disposed on the downstream side ofthe suction air filter 23 in the filtering chamber 21.

A path for supplying a water to be sprayed is communicated to thespraying apparatus 11. Water to be sprayed is supplied from a watersupplying apparatus 15 to the path.

A water adding apparatus for adding moisture to compressed air byspraying water droplets to the compressed air is disposed in a paththrough which the compressed air discharged from the compressor 2 issupplied to the combustor 4. The water adding apparatus is typicallyconfigured as a humidifier 7. A regenerator 5 is provided for receivingthe compressed air from the humidifier 7 and heating the compressed airby using gas turbine exhaust gas as a heat source. The compressed airheated by the regenerator 5 is supplied to the combustor 4.

The humidifier 7 has a path through which water is supplied to thecompressed air having been fed to the humidifier 7. Water poured fromthe water supplying apparatus 15 is supplied to the path. It may bedesirable that a path be provided for circulating recovered part of theabove poured water in order to supply the recovered water to thehumidifier 7 again. The water supplying apparatus 15 may be configuredto receive water from a water source outside the system composed of thegas turbine installation and its associated equipment, or it may beconfigured to receive water from a water source inside the systemcomposed of the gas turbine installation and its associated equipment.Alternatively, one of the water supplying apparatus 11 and thehumidifier 7 may be configured to receive water from a water sourceoutside the system and the other be configured to mainly receiverecovered water.

The humidifier 7 may be of a type in which water droplets are sprayed toflow of compressed air or a type in which water is supplied to astructure facing to a flow path through which air flows thereby bringingwater into thermal contact with the flow of compressed air. In theformer case, if the humidifier 7 is of the same spraying type as that ofthe spraying apparatus 11, most of water having been supplied tocompression air can be recovered and added to the compression air again.In the latter case, or in the former case using a general sprayingnozzle, the amount of water having been supplied to compressed air ismuch recovered, and part of the recovered water can be added tocompressed air again.

In each type, to promote evaporation of water to be supplied tocompressed air, it may be preferable to set the temperature of the waterat a high value.

The gas turbine installation in this embodiment is preferably providedwith a supplied water heater 6. The supplied water heater 6 is used forreceiving water supplied from the water supplying apparatus 15 or waterpoured to compressed air and recovered therefrom, and heating the waterby heat exchange using exhaust gas discharged from the gas turbine 1 asa heat source. Water supplied into the supplied water heater 6 is heatedonce thereat, and is supplied to the humidifier 7.

As a result, water supplied to the humidifier is easy to be evaporated.Water supplied to the supplied water heater 6 is heated once thereat,and is then supplied to the humidifier 7 as incoming water.

The provision of the supplied water heater 6 is advantageous inrecovering thermal energy, which has been conventionally discharged asexhaust gas into atmospheric air, by the supplied water heater 6,thereby improving the output power and power generating efficiency ofthe gas turbine power generating system.

The gas turbine installation in this embodiment is also preferablyprovided with an after-cooler 13. The after-cooler 13 is used forreceiving water supplied from the water supplying apparatus 15 or waterpoured in compressed air at the humidifier 7 and recovered therefrom,and heating the water by heat exchange using compressed air fed to thehumidifier 7 as a heat source. Water supplied to the after-cooler 13 isheated once, and is supplied to the humidifier 7.

The provision of the after-cooler 13 is advantageous in that since thetemperature of water supplied to the humidifier is increased and therebythe water is easy to be evaporated, the humidifier can be miniaturizedas compared with that in combination with no after-cooler on the basisof the same added amount of water. Another advantage of provision of theafter-cooler 13 is that since the temperature of air led to thehumidifier becomes lower and thereby the temperature of the humidifiedair at the outlet of the humidifier can be made lower, the temperaturerange of thermal recovery from gas turbine exhaust gas performed at theregenerator 5 becomes wider, with a result that it is possible torecover thermal energy which has been discharged as exhaust gas inatmospheric air and hence to improve the output power and powergenerating efficiency of the gas turbine power generating system.

More preferably, as shown in FIG. 1, the supplied water heater 6 and theafter-cooler 13 are both provided in the gas turbine installation.

The gas turbine installation is also provided with a control unit 18.The control unit 18 is used for controlling the amounts of watersupplied to the spraying apparatus 11, the humidifier 7, and theafter-cooler 13, and the amount of water having been supplied tocompressed air at the humidifier, being recovered, and circulated in theafter-cooler 13 or the supplied water heater 6.

The operation of the above-described system will be described below.

Air 20 entered from atmospheric air into the suction air filteringchamber 21 is sprayed with water droplets by the spraying apparatus 11,and is led to the inlet of the compressor 2 through the suction airchamber 22. The air 20 is compressed to typically about 15 atm by thecompressor 2 and is discharged (for example, at about 360° C.). Thedischarge pressure may be set at 20 atm or more depending on the kind ofthe gas turbine. The compressed air discharged from the compressor 2 isfed to the after-cooler 13. The temperature of the compressed air isreduced by the after-cooler 13. The compressed air is then led to thehumidifier 7. At the humidifier 7, water having been heated to a hightemperature by heat recovery at the after-cooler 13 and the suppliedwater heater 6 flows from top to bottom, and air having been cooled atabout 100° C. by the after-cooler 13 flows from bottom to top, so thatthe flow of air is brought into direct-contact with the counter flow ofhot water, whereby the moisture content in air is increased. The airflows out of the humidifier 7 in the form of saturated air (highmoisture air) with its temperature increased to about 140° C. and withits relative humidity increased to about 100%, and flows in theregenerator 5. The high moisture air having entered the regeneratorreceives thermal energy from gas turbine exhaust gas, to be heated to ahigh temperature, and is fed into the combustor 4. At the combustor 4,fuel 50 is burned together with the high moisture air fed thereto, andhigh temperature combustion gas is fed from the combustor 4 to the gasturbine 1. The gas turbine 1 drives the power generator 3. Thecombustion gas having passed through the gas turbine 1 flows out of thegas turbine 1 in the form of high temperature exhaust gas, passingthrough the regenerator 5 and the supplied water heater 6, and isdischarged in atmospheric air.

In addition, water used in the spraying apparatus 11 and the humidifier7 are supplied from the water supplying apparatus 15.

The function of the above-described system configuration, which iscapable of increasing the output power and power generating efficiencyof the system, will be described below.

Air having entered the suction air chamber 22 is sprayed with waterdroplets by the spraying apparatus 11 as described above. At this time,water droplets sprayed to the air is partially evaporated to cool theair. The air flows in the inlet of the compressor 2. When air is cooled,the density of the air becomes large. Accordingly, the flow rate inweight of the air flowing in the compressor is increased. As a result,an effect of increasing the output power of the gas turbine can beobtained.

In the compressor, the air is compressed and thereby the temperature ofthe air is increased, with a result that the water droplets remainingnon-evaporated in the air having been led to the compressor 2 absorbevaporation latent heat from the surrounding air, to be therebyevaporated. Accordingly, in the case where water droplets are added, theair temperature at the outlet of the compressor is made lower than thatin the case where water droplets are not added. The compression work ofthe air compressor is dependent on the temperatures at the inlet andoutlet of the compressor, and if the temperature rise of air at theoutlet of the compressor is suppressed, the compression work of thecompressor is reduced. For the gas turbine, 50% or more of the outputpower generated by the gas turbine is consumed as a power required forthe compressor, and for the gas turbine having a higher compressionratio, the percentage of the output power consumed as the power requiredfor the compressor becomes further larger. Accordingly, the reduction incompression work of the compressor leads to the increase in net outputpower of the gas turbine.

The water droplets sprayed to the air by the spraying apparatus 11 areevaporated during a period in which they flow down in the suction airchamber extending to the inlet of the compressor and in the compressor,to produce moisture containing compressed air at a high temperature (forexample, about 360° C.). The compressed air is cooled once by theafter-cooler 13, to become moisture containing compressed air at about100° C., and is led to the humidifier 7. The humidifier is provided forincreasing the moisture content in the compressed air. Heat recoveredfrom gas turbine exhaust gas via the supplied water heater 6 or heatpossessed in the compressed air is used as thermal energy necessary forevaporation of water in the humidifier. To improve the power generatingefficiency of the power generating system, it may be desirable toeffectively recover heat in a temperature range being as low as possibleand hence to make heat to be discharged to the outside as small aspossible. The combination of the after-cooler and the humidifier canobtain water at a low temperature on the basis of the same principle asthat for a cooling tower making use of a phenomenon in which uponevaporation of water, the water loses the latent heat, to lower thetemperature thereof. Accordingly, it is possible to recover heat in alower temperature range, and hence to improve the power generatingefficiency of the power generating system.

The high moisture air flows out of the humidifier 7 as saturated airwith its temperature increased to about 140° C. and its relativehumidity increased to 100%, and flows in the regenerator 5. Thesaturated air thus supplied in the regenerator 5 absorbs heat recoveredfrom gas turbine exhaust gas, to become high temperature air kept at,for example, about 550° C. at the outlet of the regenerator 5. The hightemperature air flows in the combustor 4. In the combustor 4, fuel isburned together with the high temperature air, to produce combustion gasat a specific temperature. In such a system provided with theregenerator 4, since the air used for combustion is heated at a hightemperature by the regenerator, the necessary fuel amount becomessmaller than that in the system provided with no regenerator. In thisway, the use of the regenerator gives a large effect to improvement inpower generating efficiency of the power generating system.

In the case of operating the system with the combustion temperaturecontrolled to a specific value, if the amount of moisture contained inair supplied to the combustor 4 becomes larger, the oxygen concentrationin the air becomes smaller. According to the system in this embodiment,however, since the amount of water required to be supplied for obtainingthe same output power and power generating efficiency can be madesmaller than that in the related art system in which water is added toair having been already compressed, the oxygen concentration of the airsupplied to the combustor 4 can be made higher, to thereby attain morestable combustion. Further, according to the system in this embodiment,the necessary fuel amount for obtaining the same output power and powergenerating efficiency can be made smaller than that in a system usingonly the spraying apparatus 11 for adding water to air, so that it ispossible to further increase the power generating efficiency of thepower generating system.

In the turbine 1, since a large amount of moisture is contained incombustion gas, the flow rate of the combustion gas is increased inproportional to the added amount of moisture, thereby increasing theoutput power of the turbine; and since water vapor having a specificheat larger than that of air is mixed in the air, the specific heat ofthe mixed gas becomes large, with a result that the work obtained whenthe compressed mixed gas is expanded in the turbine is increased. As aresult, the output power of the turbine 1 is increased by the above twoeffects.

In this way, according to this embodiment, it is possible to attainstable combustion while improving the output power and power generatingefficiency of the power generating system, and hence to attain highlyefficient, stable combustion even upon partial loading.

Further, according to this embodiment, the system includes the sprayingapparatus 11 and the water adding apparatus 7. The spraying apparatus 11is disposed in the suction air chamber 22 on the upstream side of thecompressor 2 and is used for spraying water to air to be supplied to thecompressor 2 so as to lower the temperature of the air to be supplied tothe compressor 2 than that of atmospheric air, wherein water dropletssprayed on the air are evaporated in a period in which the waterdroplets led in the compressor 2 together with the air whose temperaturehas been lowered flow down in the compressor 2. The water addingapparatus 7 is used for adding water to the compressed air containingmoisture added by the spraying apparatus 11 and discharged from thecompressor 2. With this configuration, the system can be highlyefficiently operated at a high output power in a state in which theamount of water added in compressed air supplied to the combustor isreduced.

The system in this embodiment, therefore, has the feature in which thesame output power and power generating efficiency can be attained with areduced amount of water added in the compressed air supplied to thecombustor as compared with the system in which moisture is added to airhaving been already compressed by the compressor.

Such a function of the system will be described below.

First, the reason why the amount of water added to the compressed airsupplied to the combustor in the system of the present invention can bemade smaller than that in the related art system will be described.

According to the related art system of adding moisture to compressed air(high moisture gas turbine system, for example, HAT system), moisture isadded to air for combustion by a humidifier, and in this case, heatrecovered from gas turbine exhaust gas by a supplied water heater, heatrecovered by intermediate cooling by a compressor, and heat possessed bythe compressed air itself are used for thermal energy required forevaporating water in the humidifier. On the other hand, according to thesystem of the present invention, as described above, since theintermediate cooler is not used, heat recovered by the intermediatecooler is not present; and fine water droplets are sprayed to air to besupplied to the compressor and are evaporated until they flow into thecompressor and in the compressor, whereby moisture is somewhat added tothe air for combustion before the air flows in the humidifier.

FIG. 2 shows the increment in output power of the system of the presentinvention on the basis of the output power of a comparative system undera condition with the same amount of supplied water. The comparativesystem includes a low pressure compressor and a high pressure compressorarranged in series and an intermediate cooler, wherein water is added tocompressed air discharged from the high pressure compressor. Accordingto the system of the present invention, moisture is added in two stages:in the front stage in which moisture is sprayed to air before the airflows in the compressor, and in the rear stage in which moisture isadded to the compressed air discharged from the compressor (for example,by the humidifier), and accordingly, the ratio of the amount of watersprayed to the air before the air flows in the compressor to the totalamount of supplied water is indicated on the abscissa. In the figure,when the amount of water sprayed to suction air is zero, the totalamount of supplied water is equivalent to the amount of water added tothe compressed air by the humidifier.

In FIG. 2, a broken line shows data obtained by the related art systemin which water is added by the intermediate cooler and also water isadded to compressed air discharged from the high pressure compressor. Inthis case, the ratio of the amount of water added by the intermediatecooler to the total amount of supplied water is indicated on theabscissa.

From the results shown in FIG. 2, it is evaluated that as the ratio ofthe amount of water supplied by the spraying apparatus 11 to the totalamount of supplied water becomes larger, the increment in output powerof the system of the present invention on the basis of the output powerof the comparative system becomes larger.

Accordingly, when the system of the present invention is compared withthe comparative system under a condition with the same output power, asthe ratio of the amount of water supplied by the spraying apparatus 11of the system of the present invention to the total amount of suppliedwater becomes larger, the used amount of water becomes smaller than thatin the comparative system. As a result, the system of the presentinvention can obtain more stable combustion while ensuring a high outputpower and a high power generating efficiency, thereby increasing thereliability of the gas turbine installation.

The reason for this will be described on the basis of the mechanism inwhich the output power is increased by making large the ratio of theamount of water sprayed to suction air.

As described above, the addition of water to suction air to be suppliedto the compressor by spraying increases the output power of the gasturbine. This causes the following four effects:

(1) a first effect in which suction air is cooled and is increased indensity until it flows in the compressor, so that the flow rate inweight of the air to be supplied to the compressor is increased, tothereby increase the output power of the turbine;

(2) a second effect in which when being evaporated in the compressor,water droplets absorb evaporation latent heat from the surrounding gas,so that the temperature rise of the air compressed and thereby intendedto be increased in temperature is suppressed, to thereby reduce thecompression work of the compressor;

(3) a third effect in which the flow rate on the turbine side isincreased in proportional to the evaporated amount of water droplets, tothereby increase the output power of the turbine; and

(4) a fourth effect in which since water vapor having a specific heatlarger than that of air is mixed in the air, the specific heat of themixed gas becomes large, with a result that the work obtained when thecompressed mixed gas is expanded in the turbine is increased.

The system of the present invention exhibits the above effects (1) to(4); however, the comparative system does not exhibit the effects (1)and (2) but exhibits the effects (3) and (4) by adding the moisture tothe compressed air.

On the other hand, FIG. 2 also shows the increment in power generatingefficiency of the system of the present invention on the basis of thepower generating efficiency of the comparative system. From the resultsshown in FIG. 2, it is evaluated that the ratio of the amount of watersupplied by the spraying apparatus 11 to the total amount of suppliedwater becomes larger, the increment in efficiency of the system of thepresent invention on the basis of the efficiency of the comparativesystem becomes larger.

Accordingly, when the system of the present invention is compared withthe comparative system under a condition with the same efficiency, asthe ratio of the amount of water supplied by the spraying apparatus 11of the system of the present invention to the total amount of suppliedwater becomes larger, the used amount of water becomes smaller than thatin the comparative system.

For a gas turbine system in which the spraying apparatus 1 is simplyprovided to the compressor, since the compression work is reduced, theeffect of increasing the output power becomes large; however, since thetemperature of the air at the outlet of the compressor is lowered, thatis, the temperature of the air to be supplied to the compressor islowered, the used amount of fuel at the combustor becomes large, so thatit is not expect to increase the power generating efficiency.

In the comparative system in which water is supplied to compressed air,if the used amount of water is set to a value, the output power and thepower generating efficiency are correspondingly determined at respectivevalues. As a result, if it is intended to improve the output power andthe power generating efficiency by strengthening intermediate cooling,heat recovered by intermediate cooling is consumed to increase theamount of moisture added to the compressed air in the humidifier. Thatis to say, to improve the output power and the power generatingefficiency, the mount of water must be increased.

On the contrary, the system in this embodiment includes the sprayingapparatus 11, the humidifier 7, and the regenerator 5. The sprayingapparatus 11, provided in the air suction chamber 22 disposed on theupstream side of the compressor 2, is used for spraying water dropletsto air to be supplied to the compressor 2 thereby making the temperatureof the air to be supplied to the compressor 2 lower than the temperatureof atmospheric air. The sprayed water droplets are introduced in thecompressor 2 together with the air whose temperature has been loweredand are evaporated in a period in which the water droplets flow down inthe compressor 2 together with the air. The humidifier 7 is used foradding water to the compressed air which contains moisture added in theform of water droplets by the spraying apparatus 11 and which isdischarged from the compressor 2. The regenerator 5 is used forreceiving the compressed air containing moisture added by the humidifier7 and heating the compressed air by using a gas turbine exhaust gas as aheat source. Accordingly, the system can reduce the compression workwhile suppressing the reduction in the temperature of the compressed airto be supplied to the combustor. In particular, the system has asignificant effect in which since the air for combustion is heated bythe regenerator, even when moisture is added to the air, the outputpower can be increased while the used amount of fuel in the combustor islittle increased. In addition, according to this embodiment, under acondition with the same supplied amount of water as that in thecomparative system, the output power and the power generating efficiencycan be improved by increasing the ratio of the amount of water sprayedto air by the spraying apparatus 11 to the amount of water added to airby the humidifier 7. In other words, according to this embodiment, undera condition with the same output power and the power generatingefficiency, the moisture content in the compressed air to be supplied tothe combustor 4 can be reduced, with a result that the combustionstability can be improved.

In the related art system including the intermediate cooler for reducinga power for the compressor, there occur a pressure loss and a heatradiation loss accompanied by the heat exchanger; however, in the systemof the present invention in which water is sprayed to suction air, therelittle occur these losses, to thereby effectively improve the outputpower and the power generating efficiency.

The size of the water droplets sprayed from the spraying apparatus 11 isset to be 30 μm or less, preferably, 10 μm or less from the viewpoint ofsuppressing erosion of blades. The lower limit of the size of the waterdroplets may be set at about 1 μm in consideration of the technicalviewpoint and energy required for production of fine water droplets.

If a silencer is disposed in the suction air chamber 22, the sprayingapparatus 11 is preferably located on the downstream side of thesilencer. For example, the spraying apparatus 11 can be located inproximity to the downstream end of the silencer. If a screen or the likeis disposed in the suction air chamber 22, the spraying apparatus 11 ispreferably located, for example, on the downstream side of the screenfrom the viewpoint of adhesion of sprayed water droplets on the screen.

The ratio of the amount of water sprayed to air by the sprayingapparatus 11 to the amount, of water added to compressed air by thehumidifier 7 is preferably controlled to be in a range of 1/50 to 1/5,preferably, 1/25 to 1/10.

By controlling the ratio between both the water amounts at a value inthe above range, it is possible to obtain a more substantial effect, toattain stable combustion, and to improve the stability of equipment ofthe system. However, it may be desirable to suitably adjust the upperand lower limits of the above range depending on characteristics of theequipment.

The system in this embodiment includes the spraying apparatus 11 and thehumidifier 7, wherein heat of water recovered by the humidifier 7 isrecovered by the after-cooler 13 or the supplied water heater 6. Thespraying apparatus 11, provided in the air suction chamber 22 disposedon the upstream side of the compressor 2, is used for spraying waterdroplets to air to be supplied to the compressor 2 thereby making thetemperature of the air to be supplied to the compressor 2 lower than thetemperature of atmospheric air. The sprayed water droplets areintroduced in the compressor 2 together with the air whose temperaturehas been lowered and are evaporated in a period in which the waterdroplets flow down in the compressor 2 together with the air. In thiscase, most of the amount of sprayed water flows together with thesuction air, and thereby recovered water is not substantially present orlittle present. The humidifier 7 is used for adding water to compressedair, which contains moisture added in the form of water droplets by thespraying apparatus 11 and which is discharged from the compressor 2, bybringing the compressed air into contact with water flowing in astructure disposed facing to the flow path of the compressed air. Inthis case, part of the supplied water is added to the air and theremaining water is recovered. With this configuration, it is possible toensure a sufficient recovered calorie and to operate the system with ahigher output power.

Further, the system of the present invention preferably furtherincludes: a control unit for controlling the amount of water added toair in such a manner that the amount of water sprayed to the air by thespraying apparatus 11 is in a range of 1/50 to 1/5 of the amount ofwater added to the compressed air by the humidifier 7; wherein the ratioof the amount of circulated water to and from the humidifier 7 to theamount of water added to the compressed air by the humidifier 7 ispreferably controlled to be in a range of 70% to 95%.

By setting the ratio between both the water amounts at a value in theabove range, it is possible to ensure a sufficient recovered calorie, toattain stable combustion, and to obtain a high output power and a highpower generating efficiency.

The ratio of the amount of water sprayed by the spraying apparatus 11 tothe flow rate in weight of the air is preferably controlled to be in arange of 0.2% to 5.0%, preferably, 0.4% to 2.5%; while the ratio of theamount of water sprayed by the humidifier 7 to the flow rate of thecompressed air discharged from the compressor is preferably controlledto be in a range of 1.0% to 30%.

The supply of water to air upon starting the system may be performed inthe following manner:

In a period from a starting point to a time point in which the gasturbine is applied with a loaded, the supply of sprayed water by thespraying apparatus is stopped, and compressed air is allowed to flow ina bypass line (not shown) for leading the compressed air discharged fromthe compressor 2 to the regenerator 5 while bypassing the humidifier 7and/or the after-cooler 13.

In the subsequent period until rated operation, the supply of water bythe spraying apparatus 11 remains stopped, and the compressed airdischarged from the compressor 2 is allowed to flow from the bypass lineto the humidifier 7 and/or the after-cooler 13 and water is added to thecompressed air at the humidifier 7.

In the period after rated operation, water is sprayed by the sprayingapparatus 11, to thereby start the gas turbine in a short time.

In the case of a change in load, the supply of water to air iscontrolled as follows:

When the load is reduced, the amount of water added to the compressedair by the humidifier 7 is reduced and then the amount of water sprayedby the spraying apparatus is reduced.

When the amount of water added to the compressed air by the humidifier 7is reduced, the amount of fuel 50 may be reduced together with theamount of water, as needed.

When the load is increased, the amount of water sprayed by the sprayingapparatus 11 is increased and then the amount of water added to thecompressed air by the humidifier 7 is increased.

With this configuration, in addition to the above-described effects,there can be obtained an effect of capable of operating the system at ahigh efficiency upon partial loading.

It should be noted that the above description of the control is forillustrative purposes only, and it is to be understood that the presentinvention is not limited thereto.

A second embodiment will be described with reference to FIG. 3.

FIG. 3 is a schematic diagram showing another embodiment of the presentinvention.

The embodiment shown in FIG. 3 is different from that shown in FIG. 1 inthat the water supplying apparatus 15 is replaced with a water recoveryapparatus 8 for recovering moisture contained in exhaust gas. To be morespecific, in addition to the configuration shown in FIG. 1, the waterrecovery apparatus 8 is provided for receiving combustion exhaust gashaving passed through the regenerator 5 (or combustion exhaust gashaving passed through the supplied water heater 6 if the supplied waterheater 6 is provided) and recovering moisture from the exhaust gas. Awater processing apparatus 10 is also provided for purifying waterrecovered by the water recovery apparatus 8. The water purified by thewater processing apparatus 10 is led to the spraying apparatus 11 or thehumidifier 7.

Preferably, as shown in FIG. 3, in addition to the above configuration,an exhaust gas reheater 9 is provided for receiving exhaust gas havingpassed through the supplied water heater 6 and exhaust gas having passedthrough the water recovery apparatus 8 and performing heat exchangeusing the exhaust gases.

If the recovered water is insufficient, water to be supplied to thespraying apparatus 11 or the humidifier 7 is supplied from outside thesystem. Preferably, recovered water is preferentially supplied to thehumidifier 7. To be more specific, the recovered water is led to thehumidifier 7, and if the amount of the recovered water is more than theamount of water to be supplied to the humidifier 7, the excess amount ofthe recovered water is supplied to the spraying apparatus 11. To thespraying apparatus, water may be supplied from outside the system asneeded.

In this embodiment, exhaust gas having passed through the regenerator 5(or supplied water heater 6) is supplied to the exhaust gas reheater 9.At the reheater 9, the exhaust gas is subjected to heat exchange withlow temperature exhaust gas whose moisture has been recovered by thewater recovery apparatus 8, to be lowered in temperature, and is thensupplied to the water recovery apparatus 8. At the water recoveryapparatus 8, the moisture is recovered from the exhaust gas thussupplied thereto. One example of recovering moisture from exhaust gas isto cool the gas to a saturated temperature (dew-point) or less of watervapor contained in the gas. For example, the temperature of the exhaustgas may be lowered by cooling water supplied from outside the system.The exhaust gas emerged from the water recovery apparatus 8 is heated bythe exhaust gas reheater 9, and is discharged from an exhaust tower (notshown) to atmospheric air.

It may be considered that carbon dioxide or impurities in the combustionexhaust gas be dissolved in the recovered water, and therefore, therecovered water is purified by the water processing apparatus 10. Therecovered water thus purified is reused as water to be added tocompressed air by the humidifier 7 or as water to be sprayed to air bythe spraying apparatus 11. As water to be sprayed to air by the sprayingapparatus 11, water supplied from the water supplying apparatus 15 (notshown) may be used in place of the recovered water.

This embodiment is characterized in that moisture recovered from exhaustgas is reused.

The ratio of the amount of the recovered water to the amount of moisturecontained in exhaust gas is dependent on the degree of cooling theexhaust gas by the water recovery apparatus. If the exhaust gas isentirely cooled to about 38° C., it is possible to obtain recoveredwater to an extent equivalent to the amount of water to be supplied toair. In this case, it is possible to realize a system in which only therecovered water is reused and the necessity of newly supplying water issubstantially eliminated. In general, industrial water having beensubjected to water processing is used as water to be newly supplied toair. From the viewpoint of thermal energy, the temperature of industrialwater is often equal to or somewhat lower than the temperature ofatmospheric air. On the other hand, the temperature of water recoveredfrom exhaust gas is in the order of about 38° C., which is higher thanthe temperature of atmospheric air. Further, recovered water whosetemperature is in a higher range of about 60° C. can be obtained byoptimizing the recovering manner. In this embodiment, the temperature ofwater to be supplied to the humidifier 7 is about 180° C., and such hightemperature water is obtained by heat exchange using various heatexchangers. Accordingly, the temperature of water to be supplied to thehumidifier is desirable to be as high as possible.

In this embodiment, since moisture recovered from exhaust gas is reusedas water to be supplied, the temperature of the water to be supplied ishigher than that of general industrial water. In other words, assumingthat the calorie for obtaining high temperature water to be supplied tothe humidifier is fixed, in the case of using the recovered water, theheat recovery amount by various heat exchangers can be made lower thanthat in the case of using industrial water. This is effective tominiaturize the heat exchanger or to reduce the flow rate of acirculated heat exchange medium. With this configuration, since thepressure loss of equipment connected to the gas turbine is reduced, itis possible to enhance the power generating efficiency. Further, in thisembodiment, since the recovered water containing heat from thecombustion exhaust gas can be used and the heat generated by the gasturbine can be returned to the upstream side of the combustor to be thusreused, the power generating efficiency of the gas turbine is madehigher than that in the embodiment shown in FIG. 1. Further, the systemin this embodiment can be operated at a high power generating efficiencyeven upon partial loading.

If evaporated liquid natural gas is used as fuel 50, a fuel heater forheat exchange of the fuel 50 with water flowing in a water supply pathcommunicated to the spraying apparatus 11 can be provided in a fuelsupply path. The fuel to be led to the combustor 4 i s heated by waterflowing to the spraying apparatus 11. The water whose temperature hasbeen lowered by heat exchange at the fuel heater is supplied to thespraying apparatus 11.

A third embodiment will be described with reference to FIG. 4.

FIG. 4 is a schematic view showing a further embodiment of the presentinvention.

The embodiment shown in FIG. 4 is different from the embodiment shown inFIG. 3 in that a direct contact type water recovery apparatus 8 forspraying cold water is provided and a water supply path through whichwater is supplied to the spraying apparatus 11 is different from a watersupply path through which water is supplied to the humidifier 7.

To be more specific, in addition to the configuration shown in FIG. 1,the water recovery apparatus 8 is provided for receiving combustionexhaust gas having passed through the regenerator 5 (or combustionexhaust gas having passed through the supplied water heater 6 if thesupplied water heater 6 is provided) and recovering moisture from theexhaust gas. A water processing apparatus 10 is provided for purifyingwater recovered by the water recovery apparatus 8. Further, acirculation water cooler 14 is provided for cooling the water recoveredby the water recovery apparatus 8. The water recovered by the waterrecovery apparatus 8 is supplied to the water supply path communicatedto the humidifier 7, and the water recovered by the water recoveryapparatus 8 and lowered in temperature is supplied to the water supplypath communicated to the spraying apparatus 11.

Preferably, as shown in FIG. 4, in addition to the above configuration,an exhaust gas reheater 9 is provided for receiving exhaust gas havingpassed through the supplied water heater 6 and exhaust gas having passedthrough the water recovery apparatus 8 and performing heat exchangeusing the exhaust gases.

The exhaust gas having passed through the regenerator 5 (or suppliedwater heater 6) is supplied to the exhaust gas reheater 9, and islowered in temperature by the exhaust gas having passed through thewater recovery apparatus 8. The exhaust gas thus lowered in temperatureis supplied to the water recovery apparatus 8. At the water recoveryapparatus 8, moisture is recovered from the above exhaust gas. Theexhaust gas emerged from the water recovery apparatus 8 passes throughthe exhaust gas reheater 9, being heated by the reheater 9, and isdischarged from an exhaust tower (not shown) to atmospheric air.

One part of the water recovered by the water recovery apparatus 8 is ledto the humidifier 7 via the water processing apparatus 10, and the otherpart is cooled by the circulation water cooler 14 and is led to thewater recovery apparatus 8 again to be recovered. The water cooled bythe circulation water cooler 14 is partially supplied to the sprayingapparatus 11. Any water is purified before being supplied, as needed.

The spraying apparatus 11 is expected to cool suction air for the gasturbine, and to achieve such a purpose, the temperature of water to besupplied to the spraying apparatus 11 may be desirable to be low. On theother hand, since water to be supplied to the humidifier 7 is heated ata high temperature by thermal recovery before being supplied to thehumidifier 7, the temperature of the water to be supplied to thehumidifier 7 may be desirable to be high. For this reason, according tothe system of the present invention, part of the water emerged from thecirculation water cooler 14 is branched to the spraying apparatus 11,and the recovered water being highest in temperature in the waterrecovery loop is supplied to the humidifier 7. With this configuration,since the water recovery effect becomes high and also the suction aircooling effect becomes large, it is expected to increase the outputpower of the system. Also, it is possible to increase the amount ofrecovered water, and to decrease the amount of water to be supplied.Further, since the temperature of water to be supplied to the humidifier7 becomes high, the humidifier and the heat exchanger for recovery ofexhaust gas can be miniaturized, to reduce the pressure loss, therebyimproving the power generating efficiency.

As a result, the system can be operated with a high power generatingefficiency and a high output power under stable combustion. Further, itis possible to improve the power generating efficiency upon partialloading.

The concrete example of the water recovery apparatus 8 will be describedwith reference to FIG. 6.

The condensation latent heat of water vapor under a condition ofatmospheric pressure and 40° C. is about 570 kcal/kg. In the case ofcondensing 1 kg of the water vapor by spraying cold water (thetemperature rise of the cold water is taken as 10° C.), since thespecific heat of water is about 1 kcal/kgK, the necessary flow rate ofthe sprayed water becomes about 57 kg. The flow rate of sprayed waternecessary for recovery of water from exhaust gas, that is, forcondensation of water vapor is required to be several ten times the flowrate of the water vapor, although it is dependent on the designcondition of the water recovery apparatus. By optimizing the waterrecovery manner, it is possible to separate high temperature recoveredwater from low temperature sprayed water. FIG. 6 shows a configurationfor obtaining high temperature recovered water.

In this embodiment, two kinds of water, that is, high temperature waterand low temperature water are recovered from the water recoveryapparatus 8. The high temperature recovered water is supplied to thehumidifier 7, and the lower temperature recovered water is supplied tothe spraying apparatus 11.

Combustion exhaust gas containing a large amount of water vapor, whichhas passed through the supplied water heater 6, is cooled by a heatexchanger (for example, the exhaust gas reheater 9), and then it flowsin the water recovery apparatus 8. At the water recovery apparatus 8,the combustion exhaust gas is brought into direct-contact with coolingwater to be cooled into wet water vapor. Part of the water vapor iscondensed to be recovered. The remaining exhaust gas is heated by theheat exchanger and is discharged to atmospheric air via a chimney. Thewater recovery apparatus 8 is composed of a plurality of water recovermeans which are arranged in series against the gas flow. Each waterrecovery means includes a cooling water scattering portion forscattering cooling water to the flowing exhaust gas, and a recoveryportion for recovering scattered water and condensed water. The waterrecover means allows exhaust gas to flow between the cooling waterscattering portion and the recovery portion. At least part of therecovered water is used as cooling water for the cooling waterscattering portion of the water recovery means positioned on theupstream side of the gas flow. The details will be described below.

In the water recovery apparatus 8, cooling water passes through a pipe41 and is scattered in exhaust gas at a cooling water scattering portion51 a, and scattered water and condensed water are recovered at a waterrecovery portion 51 b. The recovered water passes through a pipe 43 andis cooled at the circulation water cooler 14, and further it passesthrough the pipe 41 to be thus circulated as cooling water. Part of therecovered water, which has been recovered at the water recovery portion51 b, is fed to a cooling water scattering portion 52 a by way of pipes44 and 45. Since the scattered water fed to the cooling water scatteringportion 52 a absorbs condensation latent heat, it is higher intemperature than the scattered water at the cooling water scatteringportion 51 a. The scattered water at the cooling water scatteringportion 52 a is recovered by a water recovery portion 52 b, passingthrough pipes 46 and 47, and is then fed to a cooling water scatteringportion 53 a. By repeating such a process, it is possible to obtain therecovered water in a pipe 60 at the outlet of the water recoveryapparatus, which is higher in temperature than the recovered water in apipe 42. The recovered water in the pipe 60, discharged from the waterrecovery portion 59 b of the water recovery means on the uppermoststream side is reused via the water processing apparatus 10.

The exhaust gas reheater 9 is used for heating exhaust gas afterrecovery of water. In the example shown in FIG. 6, the exhaust gasreheater 9 is configured as a gas-gas heat exchanger using exhaust gasbefore recovery of water as a heat source. If another heat source can beobtained, it can be used.

Accordingly, it is possible to obtain two kinds of recovered waterdifferent in temperature, and to easily obtain high temperaturerecovered water. This makes it possible to recover thermal energypossessed by exhaust gas in a high energy state.

With this configuration, upon cooling by direct contact type spraying,it is possible to obtain high temperature recovered water and lowtemperature spray circulation water.

In the high moisture gas turbine, moisture is contained in combustiongas in an amount of about 25% to 30% in volume, and the dew point of thecombustion exhaust gas becomes about 70° C. By cooling exhaust gas to atemperature lower than the dew point, water can be recovered. And, sincethe direct contact type cooling by spraying cold water in thisembodiment is configured as described above, it is possible to obtainrecovered water having a high temperature of about 60° C. and acirculation water having a temperature of about 30° C. By making use ofsuch high temperature water as water to be supplied to the humidifier,it is possible to obtain the same effect as that in the third embodimentshown in FIG. 4.

In this way, of recovered water obtained by the water recoveredapparatus 8, a high temperature part of the recovered water is fed tothe humidifier 7 by way of the water processing apparatus 10 and thesupplied water heater 6. This makes it possible to further enhance thethermal efficiency of the plant. Meanwhile, of recovered water obtainedby the water recovered apparatus 8, a lower temperature part of therecovered water is fed to the spraying apparatus 11 as water to besprayed via the water processing apparatus 10. This is effective tofurther cool the temperature of suction air flowing in the suction airchamber 22.

A fourth embodiment will be described with reference to FIG. 5.

FIG. 5 is a schematic diagram showing a further embodiment of thepresent invention.

The embodiment shown in FIG. 5 is different from the embodiment shown inFIG. 3 in that a direct-contact type water recovery apparatus forspraying cold water is used as the water recovery apparatus 8; a watersupply path through which water is supplied to the spraying apparatus 11is different from a water supply path through which water is supplied tothe humidifier 7; and spraying apparatuses are arranged in a pluralityof steps along the flow of air in the suction air chamber 22 in such amanner that the temperature of water sprayed from one of the sprayingapparatuses positioned on the downstream side is higher than thetemperature of water sprayed from one of the spraying apparatusespositioned on the upstream side.

To be more specific, in addition to the configuration shown in FIG. 1,the water recovery apparatus 8 is provided for receiving combustionexhaust gas having passed through the regenerator 5 (or combustionexhaust gas having passed through the supplied water heater 6 if thesupplied water heater 6 is provided) and recovering moisture from theexhaust gas. A water processing apparatus 10 is provided for purifyingwater recovered by the water recovery apparatus 8. Further, acirculation water cooling apparatus 14 is provided for cooling waterrecovered by the water recovery portion 8. Water recovered by the waterrecovery apparatus 8 is supplied to the water supply path communicatedto the humidifier 7. Part of the water recovered by the water recoveryapparatus 8 is branched from a middle point of the water supply pathcommunicated to the humidifier 7 and is then supplied, as water to besprayed, to a spraying apparatus 16 which is disposed in such a manneras to be offset onto the inlet side of the compressor from the sprayingapparatus 11 in the suction air chamber 22. Water recovered by the waterrecovery apparatus 8 and is lowered in temperature is supplied to thewater supply path communicated to the spraying apparatus 11.

Preferably, as shown in FIG. 5, in addition to the above-describedconfiguration, an exhaust gas reheater 9 for receiving exhaust gashaving passed through the supplied water heater 6 and exhaust gas havingpassed through the water recovery apparatus 8 and performing heatexchange using the exhaust gases. The spraying apparatus 16 can beconfigured to exhibit the same effect as that obtained by the sprayingapparatus 11.

Low temperature water is supplied to the spraying apparatus 11 like theembodiment shown in FIG. 4, and high temperature water having atemperature similar to that of water to be supplied to the humidifier 7is supplied to the spraying apparatus 16.

With this configuration, water sprayed by the spraying apparatus 11 canexhibit a large suction air cooling effect equivalent to the outputpower increasing mechanism (1) described in the embodiment shown in FIG.1, and water sprayed by the spraying apparatus 16, which are easy to beevaporated in the compressor, can exhibit large effects equivalent tothe output power increasing mechanisms (2), (3) and (4) described in theembodiment in FIG. 1.

The reason why the water sprayed by the spraying apparatus 16 is easy tobe evaporated in the compressor may be considered to be due to the factthat since the temperature of the water is high, thermal energy requiredfor evaporation becomes small, and the fact that since the surfacetension of water becomes small as the temperature of the water isincreased, the sprayed water can be made fine and the surface area perunit weight of each fine water droplet becomes large, wherebyevaporation of the sprayed water is promoted.

As a result, it may be considered that, of the total amount of the waterdroplets sprayed by the spraying apparatuses 11 and 16, the amount ofwater evaporated until the water droplets flow to the outlet of thecompressor becomes larger than that described in the embodiment shown inFIG. 4. This makes it possible to further enhance the output power andthe power generating efficiency of the system.

In this way, according to this embodiment, the spraying apparatuses arearranged in multiple steps along the flow of the air in the suction airchamber 22 in such a manner that the temperature of water sprayed by thespraying apparatus 16 positioned on the downstream side is higher thanthe temperature of water sprayed by the spraying apparatus 11 positionedon the upstream side. As a result, suction air is cooled by the frontspraying apparatus 11 to thereby increase the flow rate in weight ofair, and water being easy to be evaporated in the compressor 22 can belargely contained in air to be supplied to the compressor 22 by sprayinghigh temperature water to the air by the rear spraying apparatus 16disposed near the inlet of the compressor 22.

With this configuration, since the ratio of the amount of water suppliedto suction air by the spraying apparatuses 11 and 16 to the amount ofwater supplied to compressed air by the humidifier becomes large, it ispossible to attain stable combustion while further enhancing the outputpower and the power generating efficiency.

In addition, the spraying apparatus 11 is disposed near the suction airfiltering chamber in the suction air chamber 22. For example, if asilencer is disposed in the suction air chamber 22, the sprayingapparatus 11 is adjacently disposed directly after the silencer. Thespraying apparatus 11 may be disposed directly after the filter in thesuction air filtering chamber 21. The spraying apparatus 16 ispreferably disposed near the inlet of the compressor in the suction airchamber 22, for example, near the boundary between the suction airchamber 22 and the inlet of the compressor 2 in the suction air chamber22. With this arrangement, since a distance from a point at which waterdroplets are sprayed by the spraying apparatus 11 to a point at whichthey flow in the compressor becomes large, it is possible to increasethe suction air cooling effect and hence to increase the output power ofthe system.

A sixth embodiment will be described with reference to FIGS. 1 and 3.

Each of the above-described embodiments can be regarded as an efficiencyincreasing apparatus which is provided in the existing gas turbineinstallation for improving the power generating efficiency. Even in thiscase, it is possible to enhance the output power and the powergenerating efficiency of the existing gas turbine installation whileensuring stability of a combustor by providing the efficiency increasingapparatus.

For example, the existing gas turbine power generating installationshown in FIG. 1 generally includes the suction air chamber 22 forsucking air 20, the compressor 2 for compressing the air suppliedthereto and discharging the compressed air, the combustor 4 for burningfuel together with the air discharged from the compressor 2, the gasturbine 1 driven by combustion gas generated by the combustor 4, and thepower generator 3 driven by the gas turbine.

An efficiency increasing apparatus including a spraying apparatus 11, ahumidifier (moisture adding apparatus) 7, and a regenerator 5 isprovided in the above existing gas turbine power generatinginstallation. The spraying apparatus 11, provided in the air suctionchamber 22 disposed on the upstream side of the compressor 2, is usedfor spraying water droplets to air to be supplied to the compressor 2,evaporating part of the sprayed water droplets until the water dropletsare led in the compressor 2, and evaporating the non-evaporated waterdroplets led in the compressor 2 together with the air in a period inwhich the water droplets flow down in the compressor 2 together with theair. The humidifier 7 is used for adding water to the compressed airwhich contains moisture added in the form of water droplets by thespraying apparatus 11 and which is discharged from the compressor 2. Theregenerator 5 is used for receiving the compressed air containingmoisture added by the humidifier 7 and heating the compressed air byusing a gas turbine exhaust gas as a heat source.

A water supply apparatus 15 is also provided for supplying water to thespraying apparatus 11 and the humidifier 7.

If necessary, an after-cooler 13 is provided for cooling the compressedair to be supplied to the humidifier 7 by using water to be supplied tothe humidifier 7 as a cold heat source. Further, a supplied water heater6 is provided for heating water to be supplied to the humidifier 7 byusing exhaust gas having passed through the regenerator 5 as a heatsource.

With this configuration, it is possible to realize a high moisture gasturbine installation capable of enhancing combustion stability whileensuring desired output power and power generating efficiency. Such agas turbine installation exhibits the same effect as that obtained inthe embodiment shown in FIG. 1.

A water supply path, through which water recovered from combustionexhaust gas having passed through the regenerator is supplied to atleast the humidifier of the group of the spraying apparatus and thehumidifier, may be provided together with or in place of the above watersupplying apparatus 15.

With this configuration, it is possible to obtain the same effect asthat obtained in the embodiment shown in FIG. 3.

What is claimed is:
 1. A gas turbine installation including a compressorfor compressing air supplied thereto and discharging the compressed air,a combustor for burning fuel together with the air discharged from saidcompressor, and a turbine driven by combustion gas generated by saidcombustor, said gas turbine installation comprising: a sprayingapparatus provided on the upstream side of said compressor for sprayingwater droplets to air to be supplied to said compressor; a water addingapparatus provided at a path leading said compressed air discharged fromsaid compressor to said combustor for adding water to said compressedair flowing in said path; a heat exchanger provided at said path on thedownstream side of said water adding apparatus for heating thecompressed air passed said water adding apparatus by exhaust gasdischarged from the gas turbine; a water recovery apparatus forrecovering moisture from exhaust gas having passed through said heatexchanger; and a path for supplying the water recovered from exhaust gasby said water recovery apparatus is supplied to at least one of saidspraying apparatus and said water adding apparatus.
 2. A gas turbineinstallation including a compressor for compressing air, a combustor forburning fuel together with the air discharged from said compressor, anda turbine driven by combustion gas generated by said combustor, said gasturbine installation comprising: a spraying apparatus provided on theupstream side of said compressor for spraying water droplets to air tobe supplied to said compressor; a water adding apparatus provided at apath leading said compressed air discharged from said compressor to saidcombustor for adding water to said compressed air flowing in said path;a heat exchanger provided at said path on the downstream side of saidwater adding apparatus for heating the compressed air passed said wateradding apparatus by exhaust gas discharged from the gas turbine; and acooling apparatus for cooling the compressed air flowing on the upstreamside of said water adding apparatus by heat exchange with the watersupplied to said water adding apparatus.
 3. A gas turbine installationincluding a compressor for compressing air supplied thereto anddischarging the compressed air, a combustor for burning fuel togetherwith the air discharged from said compressor, and a turbine driven bycombustion gas generated by sid combustor, said gas turbine installationcomprising: a spraying apparatus provided on the upstream side of saidcompressor for spraying water droplets to air to be supplied to saidcompressor; a water adding apparatus provided at a path leading saidcompressed air discharged from said compressor to said combustor foradding water to said compressed air flowing in said path; a heatexchanger provided at said path on the downstream side of said wateradding apparatus for heating the compressed air passed said water addingapparatus by exhaust gas discharged from the gas turbine; and a suppliedwater heater for heating water to be supplied to said water addingapparatus by using combustion exhaust gas having passed through saidheat exchanger as a heat source.
 4. An efficiency increasing apparatus,provided in a gas turbine installation, for recovering thermal energy ofgas turbine exhaust gas thereby improving power generating efficiency,said gas turbine installation including a compressor for compressing airsupplied thereto and discharging the compressed air, a combustor forburning fuel together with the air discharged from said compressor, anda turbine driven by combustion gas generated by said combustor; saidefficiency increasing apparatus comprising: a spraying apparatusprovided on the upstream side of said compressor for spraying waterdroplets to air to be supplied to said compressor; a water addingapparatus provided at a path leading said compressed air discharged fromsaid compressor to said combustor for adding water to said compressedair flowing in said path; a heat exchanger provided at said path on thedownstream side of said water adding apparatus for heating thecompressed air passed said water adding apparatus by exhaust gasdischarged from the gas turbine; and a path for supplying waterrecovered from combustion exhaust gas having passed through said heatexchanger to at least one of said spraying apparatus and said wateradding apparatus.
 5. A gas turbine installation including a compressorfor compressing air, a combustor for burning fuel together with the airdischarged from said compressor, and a turbine driven by combustion gasgenerated by said combustor, said gas turbine installation comprising: aspraying apparatus provided on the upstream side of said compressor forspraying water droplets to air to be supplied to said compressor; awater adding apparatus provided at a path leading said compressed airdischarged from said compressor to said combustor for adding water tosaid compressed air flowing in said path; a regenerator forheat-exchanging between the compressed air passed said water addingapparatus and exhaust gas discharged from the gas turbine; a waterrecovery apparatus for recovering moisture from exhaust gas havingpassed through said regenerator; a path for supplying the waterrecovered from exhaust gas by said water recovery apparatus is suppliedto at least one of said spraying apparatus and said water addingapparatus.
 6. A gas turbine installation including a compressor forcompressing air, a combustor for burning fuel together with the airdischarged from said compressor, and a turbine driven by combustion gasgenerated by said combustor, said gas turbine installation comprising: aspraying apparatus provided on the upstream side of said compressor forspraying water droplets to air to be supplied to said compressor; awater adding apparatus provided at a path leading said compressed airdischarged from said compressor to said combustor for adding water tosaid compressed air flowing in said path; a regenerator forheat-exchanging between the compressed air passed said water addingapparatus and exhaust gas discharged from the gas turbine; a coolingapparatus for cooling the compressed air flowing on the upstream side ofsaid water adding apparatus by heat exchange with the water supplied tosaid water adding apparatus.
 7. A gas turbine installation including acompressor for compressing air, a combustor for burning fuel togetherwith the air discharged from said compressor, and a turbine driven bycombustion gas generated by said combustor, said gas turbineinstallation comprising: a spraying apparatus provided on the upstreamside of said compressor for spraying water droplets to air to besupplied to said compressor; a water adding apparatus provided at a pathleading said compressed air discharged from said compressor to saidcombustor for adding water to said compressed air flowing in said path;a regenerator for heat-exchanging between the compressed air passed saidwater adding apparatus and exhaust gas discharged from the gas turbine;and a feed water heater for heating water to be supplied to said wateradding apparatus by using combustion exhaust gas having passed throughsaid regenerator as a heat source.
 8. An efficiency increasingapparatus, provided in a gas turbine installation, for recoveringthermal energy of gas turbine exhaust gas thereby improving powergenerating efficiency, said gas turbine installation including acompressor for compressing air, a combustor for burning fuel togetherwith the air discharged form said compressor, and a turbine driven bycombustion gas generated by said combustor; said efficiency increasingapparatus comprising: a spraying apparatus provided on the upstream sideof said compressor for spraying water droplets to air to be supplied tosaid compressor; a water adding apparatus provided at a path leadingsaid compressed air discharged from said compressor to said combustorfor adding water to said compressed air flowing in said path; aregenerator for heat-exchanging between the compressed air passed saidwater adding apparatus and exhaust gas discharged from the gas turbine;and a path for supplying water recovered from combustion exhaust gashaving passed through said regenerator to at least one of said sprayingapparatus and said water adding apparatus.